Protective Effect Of Notoginsenoside Rg1 On Spinal Cord Injury After Cerebral Ischemia In Rats

[Objectives]1.To observe the changes of motor neurons,glial cells and inflammatory factors of spinal cord after cerebral ischemia,and to explore the secondary pathological changes and mechanism of spinal cord after cerebral ischemia;2.To explore the protective effect of Notoginsenoside Rgl on spinal cord injury after cerebral ischemia,so as to provide theoretical basis for the prevention and treatment of spinal cord injury after cerebral ischemia.[Method]In this study,105 male SD rats were randomly divided into four groups:sham group,MCAO group,NS group and Rg1(40mg/kg)treatment group.Each group was divided into 3 d,7 d and 14 d group depend on the sampling time(n=5).The cervical enlargement of spinal cord was taken from each group at the corresponding time of perfusion.The changes of neurons,glial cells and inflammatory factors were detected by Nissl staining,immunofluorescence,immunohistochemistry and Western blot.SPSS 22.0 was used to analyze the data with one-way ANOVA and the comparison between them.When p<0.05,the difference was statistically significant.[Results](1)After permanent cerebral ischemia in rats,the changes of neurons were as follows:Nissl staining showed that the morphology of motoneurons in the anterior horn of cervical enlargement in the sham group was normal,the distribution of Nissl in the cytoplasm was uniform,and there were different degrees of neuronal pyknosis and aggregation in the MCAO group,especially at the 7 d group;there was no significant change between MCAO+NS and MCAO group,but the Nissl staining was uniform in the MCAO+Rg1 group.Immunofluorescence staining showed that TDP-43 positive marker in sham group were mainly concentrated in the nucleus,and a small amount of scattered and uneven size granules could be seen in the cytoplasm of MCAO group,especially at 7 d group;there was no significant difference between MCAO+NS group and MCAO group,and no significant change was observed in MCAO+Rg1 group;Western blot showed that the expression of TDP-43 in sham group,MCAO group and MCAO+Rg1 group had no statistical significance at 3 d point;the expression level of TDP-43 in MCAO group was significantly higher than that in sham group at 7 d and 14 d(P<0.001),and the expression of TDP-43 in MCAO+Rg1 group was slightly lower than that in MCAO group(P<0.05).(2)The changes of astrocytes were as follows:immunohistochemistry found that compared with sham group,the number of GFAP positive cells in the anterior angle of cervical dilatation increased,the number of cell branches increased and showed an active state in MCAO and MCAO+NS group at each time point,but there was no significant change in MCAO+Rg1 group compared with MCAO+NS group;Western blot showed that GFAP expression was no significant difference in MCAO group and MCAO+Rg1 group at all time points(P>0.05).(3)The changes of microglia were as follows:immunohistochemistry showed that compared with sham group,the number of positive cells of Lectin and Iba-1 in the anterior angle of cervical enlargement in MCAO group increased significantly at each time point,and some somata became bigger,showing an active state;compared with MCAO+NS group,there was no significant change in the positive cells of Lectin and Iba-1 in MCAO+Rg1 group;Western blot showed that compared with sham group,Iba-1 protein expression increased at each time point in MCAO group,which was statistically significant(P<0.001);compared with MCAO group,Iba-1 expression decreased in MCAO+Rg1 group,which was statistically significant(P<0.01).4.Western blot was used to detect the changes of inflammatory factors in cervical enlargement after cerebral ischemia as follows:compared with sham group,the expression levels of iNOS,TNF-? and IL-1? in MCAO group increased significantly at each time point,which were statistically significant(P<0.05),compared with the MCAO group,the expression of iNOS,TNF-? and IL-1? in MCAO+Rg1 decreased significantly(P<0.01).[Conclusion]1.Permanent cerebral ischemia induced the secondary spinal cord injury including neurodegeneration,proliferation of astrocytes and microglia and inflammatory response in rats;2.Notoginsenoside Rg1 might play important protective role in spinal cord injury following cerebral ischemia by improving the secondary neurodegeneration and reducing inflammatory response.